Braze composition and process of using

ABSTRACT

A composition includes the constituents, in approximate weight percentages: Chromium 15-17; Silicon 2.5-3.5; Cobalt 6.0-8.0; Aluminum 1.0-2.0; Tantalum 1.5-2.5; Boron 1.5-2.5; Yttrium 0.015-0.025; Nickel balance; and incidental impurities.

TECHNICAL FIELD

The disclosure relates generally to braze compositions for joiningcomponents. More particularly, this disclosure relates to brazecompositions for joining turbine components, where the braze compositionavoids formation of continuous centerline eutectic phase development,thus maintaining ductility of the braze joint.

BACKGROUND

The pace of change and improvement in the realms of joining components,such as but not limited to turbine components for power generation,aviation, and other fields has increased based on several factors. Suchfactors include turbomachinery constructions, higher operatingtemperatures of turbines, and accompanied intricacy of components usedin these fields. In the assembly of combustor assemblies that includemicromixer tubes within plate apertures, a process for fixing the tubesin order to stabilize the assembly and minimize vibration of the tubeswithin the plate is applied. In some instances, fixation is achieved byfriction welding, and in other instances, by use of a relativelyexpensive brazing filler, which may include gold. Such fixationprocesses can be time consuming and expensive, and may not alwaysachieve the desired result. In extreme settings, this could possiblynecessitate rework. During operation, potential vibration of themicromixer tube within the plate aperture may lead to wear that canultimately contribute to metal loss and micromixer tube tip failure,which can in turn lead to combustor inefficiency and possible failure.

BRIEF DESCRIPTION

A first aspect of the disclosure provides a composition comprising inapproximate weight percentages:

Chromium 15-17 Silicon 2.5-3.5 Cobalt 6.0-8.0 Aluminum 1.0-2.0 Tantalum1.5-2.5 Boron 1.5-2.5 Yttrium 0.015-0.025 Nickel balance, and incidentalimpurities.

A second aspect of the disclosure provides a braze material comprisingin approximate weight percentages:

Chromium 15-17 Silicon 2.5-3.5 Cobalt 6.0-8.0 Aluminum 1.0-2.0 Tantalum1.5-2.5 Boron 1.5-2.5 Yttrium 0.015-0.025 Nickel balance, and incidentalimpurities.

A third aspect of the disclosure provides a process of using a brazematerial comprising in approximate weight percentages:

Chromium 15-17 Silicon 2.5-3.5 Cobalt 6.0-8.0 Aluminum 1.0-2.0 Tantalum1.5-2.5 Boron 1.5-2.5 Yttrium 0.015-0.025 Nickel balance, and incidentalimpurities.The process comprises applying the braze material to a joint betweenturbomachine components; heating the braze material to form a moltenbraze material, to cause the braze material to flow into the joint; andallowing the molten braze material to cool, solidify, and join theturbomachine components.

A further aspect of the of the disclosure provides braze materialcomprising in approximate weight percentages:

Chromium 16 Silicon 3 Cobalt 7 Aluminum 1.5 Tantalum 2 Boron 1.5 Yttrium0.02 Nickel balance; and incidental impurities.

The illustrative aspects of the present disclosure are designed to solvethe problems herein described and/or other problems not discussed.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features of this disclosure will be more readilyunderstood from the following detailed description of the variousaspects of the disclosure taken in conjunction with the accompanyingdrawings that depict various embodiments of the disclosure, in which:

FIG. 1 illustrates schematic representation of objects joined by a brazecomposition according to embodiments of the disclosure; and

FIG. 2 illustrates a schematic representation of a wedge-shaped gapfilled with a braze composition according to embodiments of thedisclosure.

It is noted that the drawings of the disclosure are not necessarily toscale. The drawings are intended to depict only typical aspects of thedisclosure and therefore should not be considered as limiting the scopeof the disclosure. In the drawings, like numbering represents likeelements between the drawings.

DETAILED DESCRIPTION

As an initial matter, in order to clearly describe the subject matter ofthe current disclosure, it will become necessary to select certainterminology when referring to and describing relevant braze materialsand processing. To the extent possible, common industry terminology willbe used and employed in a manner consistent with its accepted meaning.Unless otherwise stated, such terminology should be given a broadinterpretation consistent with the context of the present applicationand the scope of the appended claims. Those of ordinary skill in the artwill appreciate that often a particular feature may be referred to usingseveral different or overlapping terms. What may be described herein asbeing a single part may include and be referenced in another context asconsisting of multiple features. Alternatively, what may be describedherein as including multiple features may be referred to elsewhere as asingle part.

In addition, several descriptive terms may be used regularly herein, asdescribed below. The terms “first”, “second”, and “third” may be usedinterchangeably to distinguish one component from another and are notintended to signify location or importance of the individual components.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the disclosure.As used herein, the singular forms “a”, “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprises”and/or “comprising,” when used in this specification, specify thepresence of stated features, integers, steps, operations, elements,and/or components but do not preclude the presence or addition of one ormore other features, integers, steps, operations, elements, components,and/or groups thereof. “Optional” or “optionally” means that thesubsequently described event or circumstance may or may not occur orthat the subsequently describe component or element may or may not bepresent, and that the description includes instances where the eventoccurs or the component is present and instances where it does not or isnot present.

Where an element or layer is referred to as being “on,” “engaged to,”“connected to” or “coupled to” another element or layer, it may bedirectly on, engaged to, connected to, or coupled to the other elementor layer, or intervening elements or layers may be present. In contrast,when an element is referred to as being “directly on,” “directly engagedto,” “directly connected to” or “directly coupled to” another element orlayer, there may be no intervening elements or layers present. Otherwords used to describe the relationship between elements should beinterpreted in a like fashion (e.g., “between” versus “directlybetween,” “adjacent” versus “directly adjacent,” etc.). As used herein,the term “and/or” includes any and all combinations of one or more ofthe associated listed items.

Brazing processing is largely used in the gas turbine industry. A soundbraze joint is formed when liquid braze metal moves into and fills intoa gap of the two objects to be joined under capillary force. Moreover, asound braze joint is formed with little or no centerline eutectic phasesin the braze after braze solidification and the filet is substantiallywithout porosity, as illustrated in FIG. 1. Additionally, a sound brazeis substantially devoid of lack of braze regions in the brazed joint.

In a braze process, with reference to FIG. 1, a gap G defines a gap sizeGS between the two objects or components 10 and 20 to be joined by brazeB. In certain aspects of the embodiments, objects 10 and 20 may includeturbomachinery components. Further, in other aspects as embodied by thedisclosure, objects 10 and 20 may include turbomachinery combustorcomponents, such as but not limited to tubes and plates in a micromixercombustion assembly. Gap size GS can be managed in braze processing fora solid and desired full braze that fills the volume of the gap. Foreach braze filler metal, a recommended gap size GS range is oftendetermined to obtain a sound braze joint that fills the gap volume.

For example, the recommended braze gap size range for AMDRY 100 (BNi-5)is between 0.0005″ and 0.004″ (0.012 mm and 0.1 mm) Also, therecommended braze gap size range for AMDRY DF4B is between 0.010″ and0.060″ (0.254 mm and 1.5 mm). Even though braze gap size range iscontrolled, porosity or lack of braze (LOB) can still be observed if aproper volume of braze paste is not placed outside of the braze gap.Thus, rework may be necessary.

Often, braze gap size is not uniform. This non-uniformity can due to thetolerance of the objects base material. Accordingly, LOB and porositiesin the braze may be observed via visual inspection. Again, rework may benecessary.

Moreover, if the braze gap size is larger than a recommended braze gapsize for the braze, there is a potential for continuous centerlineeutectic phase development. This continuous centerline eutectic phasedevelopment may be hard and brittle, thus decreasing ductility of thebraze joint. Continuous hard and brittle eutectic phases may causemicrofissures or macrofissures, which results in leakage and impacts thelife cycle. The decrease ductility of braze joint can result in LOB,cracking, and leaking at the braze joint, which may also require rework.

In conventional brazing of hot gas path components in a gas turbine,such as but not limited to tubes and plates in a micromixer combustionassembly, braze foils may be used for brazing between tube and plate. Ina micromixer combustion assembly, the gap size between the tube andplate may be hard to control. Accordingly, continuous eutectic phasesmay be observed in the braze joints where braze foils were used,including use when the braze gap size is larger than a certain thresholdsize.

In efforts to avoid formation of continuous eutectic phases inmicromixer combustion assemblies, gold-based braze filler has beenemployed used in the brazing process, as noted above. In some advancedgas turbine machine that includes micromixer combustion assemblies, morethan several thousand gold braze joints may be necessary, which leads toextensive use of gold and increased costs.

Therefore, as embodied by the disclosure, a braze material compositionis set forth. The braze material composition includes enhanced flowability to be utilized to fill braze gaps sized from narrow, medium, andlarge size together in one single braze thermal cycle. The brazematerial composition, as embodied by the disclosure, provides enhancedflow from a small to a large gap, which will enable sound brazes betweenobjects, including but not limited to turbomachine components. Also, thebraze material composition, as embodied by the disclosure, also avoidsthe undesirable hard and brittle centerline continuous eutectic phasewith the eutectic phase's resultant decreased ductility.

The braze material composition, as embodied by the disclosure, includesthe following constituents in the weight percent values in ranges wherevalues are approximate:

Chromium 15-17 Silicon 2.5-3.5 Cobalt 6.0-8.0 Aluminum 1.0-2.0 Tantalum1.5-2.5 Boron 1.5-2.5 Yttrium 0.015-0.025 Nickel BALANCE and incidentalimpurities.

Moreover, in accordance with one aspect of the braze materialcomposition is, in approximate weight percentages:

Chromium 16 Silicon 3 Cobalt 7 Aluminum 1.5 Tantalum 2 Boron 1.5 Yttrium0.02 Nickel BALANCE and incidental impurities.

FIG. 2 illustrates a wedge shaped gap G with braze material compositionB disposed therein per the utilization in accordance with embodiments ofthe disclosure. The braze material composition B, as embodied by thedisclosure, can flow under capillary force from gap G opening 25 throughgap G and to a terminus 26. Terminus 26 can be in gap G up to at least0.060″ (1.5 mm) and possibly further. Also, braze material compositionB, as embodied by the disclosure, can flow under capillary force intogap G up to a gap height of at least 0.020″ (0.5 mm). Therefore, brazematerial composition B can flow under capillary force and suitably fillthe volume of gaps, such as gaps in turbomachinery including but notlimited to gaps at combustors that include micromixer tubes disposed inplate apertures.

In use, the braze material composition B is applied at or to a joint orgap G. As noted above, in certain aspects of the embodiment, gap G maybe a joint between turbomachine components, for example but not limitedto gaps at combustors that include micromixer tubes disposed in plateapertures. Braze material is heated so the braze material composition Bforms a molten braze material composition B. The molten braze materialcomposition B flows into gap G under capillary forces is to cause thebraze material to flow into the gap G. Thereafter the molten brazematerial composition B can cool, solidify, and join the turbomachinecomponents.

Technical effects of the braze material composition, as embodied by thedisclosure, include, but are not limited to, elimination of undesirablecontinuous centerline eutectic phases; decreasing the internal residualstress of braze joint due to these eutectic phases; reduce the crackingtendency by increasing ductility, and lowering leakage or LOB at thebrazed gap.

Approximating language, as used herein throughout the specification andclaims, may be applied to modify any quantitative representation thatcould permissibly vary without resulting in a change in the basicfunction to which it is related. Accordingly, a value modified by a termor terms, such as “about,” “approximately” and “substantially,” are notto be limited to the precise value specified. In at least someinstances, the approximating language may correspond to the precision ofan instrument for measuring the value. Here and throughout thespecification and claims, range limitations may be combined and/orinterchanged; such ranges are identified and include all the sub-rangescontained therein unless context or language indicates otherwise.“Approximately,” as applied to a particular value of a range, applies toboth end values and, unless otherwise dependent on the precision of theinstrument measuring the value, may indicate +/−10% of the statedvalue(s).

The corresponding structures, materials, acts, and equivalents of allmeans or step plus function elements in the claims below are intended toinclude any structure, material, or act for performing the function incombination with other claimed elements as specifically claimed. Thedescription of the present disclosure has been presented for purposes ofillustration and description but is not intended to be exhaustive orlimited to the disclosure in the form disclosed. Many modifications andvariations will be apparent to those of ordinary skill in the artwithout departing from the scope and spirit of the disclosure. Theembodiment was chosen and described in order to best explain theprinciples of the disclosure and the practical application and to enableothers of ordinary skill in the art to understand the disclosure forvarious embodiments with various modifications as are suited to theparticular use contemplated.

What is claimed is:
 1. A composition consisting essentially ofcomprising in approximate weight percentages: Chromium 15-17 Silicon2.5-3.5 Cobalt 6.0-8.0 Aluminum 1.0-2.0 Tantalum 1.5-2.5 Boron 1.5-2.5Yttrium 0.015-0.025 Nickel balance, and incidental impurities.


2. The composition of claim 1, wherein the composition is a brazecomposition.
 3. The composition of claim 2, wherein the brazecomposition is configured to braze turbomachinery parts.
 4. Thecomposition of claim 3, wherein the turbomachinery parts includemicromixer tubes within plate apertures.
 5. The composition of claim 2,wherein the braze composition includes in approximate weightpercentages: Chromium 16 Silicon 3 Cobalt 7 Aluminum 1.5 Tantalum 2Boron 1.5 Yttrium 0.02 Nickel balance; and incidental impurities.


6. A braze material comprising: a composition consisting essentially ofin approximate weight percentages: Chromium 15-17 Silicon 2.5-3.5 Cobalt6.0-8.0 Aluminum 1.0-2.0 Tantalum 1.5-2.5 Boron 1.5-2.5 Yttrium0.015-0.025 Nickel balance, and incidental impurities.


7. The braze material according to claim 6, the composition includes inapproximate weight percentages: Chromium 16 Silicon 3 Cobalt 7 Aluminum1.5 Tantalum 2 Boron 1.5 Yttrium 0.02 Nickel balance; and incidentalimpurities.


8. A process of using the braze material of claim 6, the processcomprising: applying the braze material to a joint between turbomachinecomponents; heating the braze material to form a molten braze material,to cause the braze material to flow into the joint; and allowing themolten braze material to cool, solidify, and join the turbomachinecomponents.
 9. The process according to claim 8, wherein theturbomachine components include turbomachine components of a combustorassembly.
 10. The process according to claim 9, wherein the turbomachinecomponents of a combustor assembly include portions of a micromixer. 11.The process according to claim 10, wherein the portions of themicromixer include micromixer tubes within plate apertures.
 12. A brazematerial consisting essentially of comprising in approximate weightpercentages: Chromium 16 Silicon 3 Cobalt 7 Aluminum 1.5 Tantalum 2Boron 1.5 Yttrium 0.02 Nickel balance; and incidental impurities.


13. The braze material of claim 12, wherein the braze composition isconfigured to braze turbomachinery parts.
 14. The braze material ofclaim 13, wherein the turbomachinery parts include micromixer tubeswithin plate apertures.